I inherited a task from another designer (who is no longer at the company) to organize my companies DSM taxonomy. In looking into it it seems there are limited amounts of sub folders you can have ie. : Library > Subfolder1 > Sub folder 2 > Element in subfolder 2. But, I have seen some sub folder 2's have another sub-level that I don't understand how it got there... it has a bolt/nut icon next to it, and I don't know if this is relevant, but all the folders are named by platform, ie. : iOS, Android, Desktop, Etc. (This may have been done manually by the previous designer though, IDK). I should mention that at the 2nd sub-folder level there is no "+ Add Folder" button-link. I guess because the DSM limits the amount of hierarchy levels you use? So I don't know how it was created. I thought it might have been auto-created because the symbol had other nested symbols and that was the DSM's way of breaking them apart for importing into your file but that was not it.
Any help understanding how this folder was created and ended up there would be appreciated, Thanks!